Typically, it is desirable to activate dopants in semiconductors in a manner that does not allow the dopants to diffuse during activation. Typically, conventional high temperature anneals are used to activate the dopants with thermal stimulation while preventing the dopants from diffusing. Dopant activation typically requires minimal ion movement. As a result, dopants are activated in a relatively short time span when high temperature anneals are used.
High temperature annealing technologies have been created with faster dwell times to allow dopant activation with minimal thermal diffusion. Faster dwell times minimize the amount of time that the high temperatures must be sustained to activate the dopants. Examples of conventional high temperature anneals that implement fast dwell times are laser spike annealing, milli-second annealing, and rapid thermal annealing. Even though fast dwell times are used to prevent the dopants from diffusing, the high temperatures required by the conventional high temperature anneals still may exceed 1000 degrees Celsius and these high temperatures are often times not tolerable even for fast dwell times. To continue Moore's law scaling, devices and device structures are being introduced with reduced thermal tolerances, and thermal budgets are being reduced for semiconductor processing systems. For example, thermal tolerances for some semiconductor substrates during annealing have been reduced to below 400 degrees Celsius.
It is becoming common wisdom to use conventional electromagnetic (EM) wave treatments in thermal annealing and dopant activation processes. Conventional EM wave treatment heats the dopants locally, which then reduces the heat that the substrate as a whole receives. Conventional EM wave treatment does not require active heating as other conventional thermal annealing processes require. As a result, the heating that the substrate is exposed to comes from residual heating which requires reduced temperatures below 500 degrees Celsius. However, conventional EM wave treatment with reduced temperatures below 500 degrees Celsius still precludes applications that require temperatures to be reduced even further.
Conventional EM wave treatment typically implements surface waves that resonate across the surfaces of the semiconductors at EM wave frequencies where the surface waves are conventional standing waves. A conventional standing wave is a wave where each non-node remains in the same location on the semiconductor surface. Conventional EM wave treatments implementing conventional standing waves are inefficient, non-uniform, and difficult to control, which has the effect of increasing the temperatures of the conventional EM wave treatments rather than lowering the temperatures. Therefore, an effective means to implement EM wave treatments of semiconductor surfaces with lower processing temperatures is needed.